The present technology relates to a magnetic recording medium including a flexible substrate.
In recent years, a coating type magnetic recording medium in which a magnetic powder is applied on a non-magnetic support has become the mainstream of magnetic recording media for data storage. In order to increase the recording capacity per one cartridge, it is necessary to improve a surface recording density using a finely pulverized magnetic powder; however, according to a currently used coating method, a thin film is difficult to form using fine grains having a diameter of 10 nm or less.
Accordingly, a magnetic recording medium has been proposed in which a film of a CoCrPt-based metal material having a high magnetic anisotropy is formed on a flexible substrate, for example, by a sputtering method, and in addition, this material is crystallized and oriented in a direction perpendicular to the surface of the substrate. As for this magnetic recording medium, it has been desired to improve the magnetic characteristics by improvement of the orientation of a magnetic recording layer, and hence, various techniques to satisfy this desire have been studied in recent years. For example, according to Japanese Unexamined Patent Application Publication No. 2005-196885, as one of the above techniques, there has been disclosed a magnetic recording medium in which an amorphous layer, a seed layer, an under layer, a magnetic layer, and a protective layer are at least sequentially laminated on a substrate. In addition, the above technique has also disclosed that the seed layer is formed from one of Ti, Cr, Mo, W, Zr, a Ti alloy, a Cr alloy, and a Zr alloy, the under layer is formed from Ru, and the magnetic layer is formed to have a granular structure.